Layla was dying of a brain tumor when Dean and Sam met her. She was visiting Roy Le Grange in the hope he could heal her. When he was stopped from his "healing", Layla resigned herself to the fact that she would die. Dean told her that he would be praying for her which made her happier.
Given her terminal illness, she is presumably deceased.
- Julie Benz, the actress portraying Layla Rourke also portrayed Darla from Buffy the Vampire Slayer and Angel, where her character was also about to die from a terminal disease before she became a vampire.